Question- about compression and dc stage 4 cams

hello guys im currently building a k24/k20 na motor and I want to run stage 4 cams since ive been told that they make the most power for high comp builds and are recommended for 12:5 compression. my problem is I bought my pistons before the cams and the pistons I have right now are 11:5 compression CP pistons. my power goal is 300 whp. should I sell the pistons? or should I mill the head and get flat face valves to bump the compression up? id like to know what I should do with the pistons atm cause there brand new and id like move on with my build and choose the right cams. the motor will see nitrous too but id like to hit 300whp before I spray nitrous

much help would be appreciated !!!

the head will have brain crower valve train